Closure and band of connected closures

ABSTRACT

The present invention provides a closure having a closing function and reclosability that is gentle on the hands of consumers and can have a low environmental impact. The invention also provides a closure whereby the connection parts in a band of connected closures are resistant to the influences of humidity changes. The present invention is a closure having a closing function and reclosability, formed of a composite layer having a layer made of paper, and provided with a closure hole, provided in substantially a center, for closing an object to be closed, as well as an opening that is smaller than the closure hole provided at one end, the opening communicating with the closure hole. Preferably this closure comprises a synthetic resin layer laminated between two layers of paper.

TECHNICAL FIELD

The present invention relates to a closure for closing and binding theneck of a bag containing food, agricultural products or the like, and toa band of connected closures that are connected directly to one another.

BACKGROUND ART

Conventional closures are disclosed for example in Patent Document 1,Patent Document 2, Patent Document 3, Patent Document 4 and PatentDocument 5.

These conventional closures are generally formed from plastic resin. Forexample, Patent Document 4 discloses a sheet consisting of an elasticsynthetic resin material such as polypropylene, polyethylene, polyvinylchloride, nylon or the like (see Patent Document 4, paragraph [0006]).

When such a closure has connection parts, fragments may break off whenthe closure is detached, and may cause contamination. This can alsocause burr, which has been known to damage the hands.

The material used in the present invention is thick paper or paperboard,which is gentler on the hands of the user (consumer), and which may alsoreduce environmental load when the paper is made of plant material.Using thick paper also allows for the use of recycled pulp. It is alsopossible to inhibit the occurrence of fragments when a band of connectedclosures is cut apart.

Continuous closing machines are generally used for the actual closing,and the closures used in this case are in the form of a band ofconnected closures connected in a line.

Such a band of connected closures connected in a line is rolled andloaded into a compartment in the closing machine, and the closures arefed one by one from the compartment during closing. The closures beingfed from the machine are detached at roughly the same time as they areclipped around an object to be closed.

That is, in the case of closing using an existing continuous closingmachine, the connection parts need to be strong enough that they do notbreak even if pull force is applied in the feed direction of theclosures, but must also be easy to detach when closing an object to beclosed.

Patent Document 1: Japanese Patent Application Laid-open No. 2001-80654Patent Document 2: Japanese Patent Application Laid-open No. 2000-179510Patent Document 3: Japanese Patent Application Laid-open No. 2001-2092

Patent Document 4: Japanese Patent Application Laid-open No. H10-59334Patent Document 5: Japanese Patent Application Laid-open No. S57-96954

DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve

It is an object of the present invention to provide a closure which isgentle on the hands of the user (consumer), and which can be easilyreused.

Another object is to provide a closure that is made moisture-resistantby lamination of synthetic resin and/or biodegradable resin, giving itexcellent storability and machine operability in a continuous closingmachine.

Another object is to provide a closure whereby occurrence of paper dustcan be suppressed by laminating a synthetic resin and/or biodegradableresin.

Still another object is to provide a closure that has a smallerenvironmental impact than conventional closures.

Means for Solving the Problems

(1) The present invention is a closure having a closing function andreclosability, which is formed of a single paper layer or a compositelayer having at least a layer formed of paper, and which has a closurehole, provided substantially in a center part, for closing an object tobe closed, and which is further formed with, at one end, an openingsmaller than the closure hole, the opening communicating with theclosure hole.

The raw material of the layer of paper that forms the principal layer ofthe present invention is plant fiber cellulose acetate or the like.Colorants; sizing agents, clay and other fillers can also be addedthereto.

(2) The closure having a closing function and reclosability according to(1) above, having, on side faces of the closure, detachable connectionparts that are connected to other closures adjacent thereto that are ina line with the closure, when the closure and the other closures areformed as a band of connected closures.

(3) The closure according to (1) or (2) above, wherein the closure isformed of a composite layer having at least a layer formed of paper, andwherein at least one of layer or layers other than the paper layer isformed from synthetic resin and/or biodegradable resin.

Synthetic resin here means a synthetic polymer substance such as athermoplastic resin or thermosetting resin. Examples include polyvinylchloride, polystyrene, polypropylene, polyethylene, methacrylic resin,polycarbonate, polyamide, phenol resin, unsaturated polyester resin;alkyd resin, epoxy resin and the like.

A biodegradable resin is a resin containing mainly biodegradablematerials, which decompose by the action of microorganisms.

Examples of raw materials that are biodegradable include biodegradableresins having plant-derived components and biodegradable resins havingpetroleum-derived components. A mixture of a biodegradable resin havingplant-derived components with a biodegradable resin havingpetroleum-derived components may also be used.

Examples of plant-derived components include polylactic acid,polycaprolactam, polyvinyl alcohol, casein, glycerin fatty acid esters,soft polylactic acid compounds compounded from polylactic acid and palmoil containing glycerin fatty acid esters, polylacticacid/diol-dicarboxylic acid copolymer, starch-polyester resin and thelike.

Starch-polyester resin does not undergo blocking when molded and workedinto a film, and also has a blocking-prevention effect when blended withother resins, as well as having good welding properties, printingproperties and durability.

Examples of petroleum-derived components include PET (polyethyleneterephthalate) and a polybutylene adipate/terephthalate copolymer resinwhich is an aliphatic-aromatic copolyester resin having a structurebased on module units consisting of terephthalic acid/butanediol adipicacid.

In particular, a closure with low environmental impact can be providedby means of a composite layer that combines a paper layer with a layermainly made of a biodegradable resin.

(4) The closure according to (3) above, wherein the layer formed fromthe synthetic resin and/or biodegradable resin includes an orientedfilm.

Examples of the oriented film here include uniaxially oriented films andbiaxially oriented films. This is a polyethylene or other polymermaterial that has been physically stretched in order to improve thestrength and heat resistance of the film. Uniaxially oriented films havethe property of being difficult to stretch in either the vertical orhorizontal direction. Biaxially oriented films are materials that aredifficult to stretch both vertically or horizontally.

(5) The closure according to (3) or (4) above, wherein the closure isformed of a composite layer comprising layers made of paper that arelaminated on both surfaces of the layer of synthetic resin and/orbiodegradable resin.

The resin layer here may be a single layer or a composite of two or morelayers.

(6) The closure according to (3) or (4) above, wherein the closure isformed of a composite layer comprising the layers of synthetic resinand/or biodegradable resin laminated on both sides of the layer ofpaper.

The layers of synthetic resin and/or biodegradable resin in this casemay be each a single layer or a composite of two or more layers.

(7) The closure according to any one of (3) to (6) above, wherein thelayer of synthetic resin and/or biodegradable resin is formed from anyone of olefin resin, polyethylene terephthalate (PET), polystyrene (PS),acrylonitrile (AN) and PVA (polyvinyl alcohol).

(8) The closure according to any one of (1) to (7) above, wherein one ormore notches are formed in the connection parts of the closure from oneor both surfaces thereof towards an inner layer.

(9) The closure according to any one of (3) to (8) above, wherein onlythe layer made of paper in the connection parts of the closure issevered.

By severing the layer of paper and forming the connection part only fromthose layers consisting of synthetic resin and/or biodegradable resin,it is possible to provide a closure with reduced detachment strength,and to inhibit the occurrence of paper dust.

(10) The closure according to any one of (1) to (9) above, wherein theweight per unit area of the paper (hereunder, also called the “basisweight”) is 400 to 1000 g/m².

If the weight per unit area of the paper is less than 400 g/m², it willnot be strong enough to function properly as a closure, while if theweight exceeds 1000 g/m² the narrow opening will be difficult to open,and may not be sufficiently reclosable.

(11) The closure according to any one of (1) to (9) above, wherein theaverage length of fibers making up the paper is 1.0 mm to 4.0 mm.

If the average of the fiber lengths making up the paper is less than 1.0mm, it will not maintain sufficient stiffness to function as a closure,while if the fiber lengths exceed 4.0 mm, the connection part will bedifficult to sever.

(12) The closure according to any one of (1) to (11) above, wherein inkor a coating material is printed or coated on the surface of theclosure.

(13) A band of connected closures formed by connecting the closuresaccording to any one of (2) to (12) above in a line by means of theadjacent connection parts of the closures.

(14) A package product wherein the object is closed using the closureaccording to any one of (1) to (12) above.

EFFECTS OF THE INVENTION

By adopting the constitution of the present invention it is possible toprovide a closure having a closing function and reclosability that iseasy for users and reusable.

Moreover, the effect of providing a closure that is resistant to theinfluences of humidity changes while having excellent machineoperability in a continuous closing machine is achieved by laminating asynthetic resin and/or biodegradable resin.

Furthermore, the effect of suppressing the occurrence of paper dust isalso achieved by laminating a synthetic resin and/or biodegradableresin.

Another effect is to provide a closure that has less of an environmentalimpact than conventional closures.

BEST MODE FOR CARRYING OUT THE INVENTION

One example of an embodiment of the closure of the present invention isgiven below. The embodiment shown below is an example of the presentinvention, and the present invention is not limited to the embodimentdescribed below.

FIG. 1 is a plane view showing a closure of an embodiment according tothe present invention. FIG. 1 only illustrates an embodiment of aclosure of the present invention, and the form of the present inventionis not limited thereby.

The closure 1 of this embodiment is formed of a composite layer havingone layer of thick paper. As shown in FIG. 1, the closure 1 of thisembodiment has closure hole 2, roughly in the center of the plane view,for closing a bag or other object to be closed. An opening 3, whichcommunicates with and is smaller than closure hole 2, is formed at oneend of the closure. The closure also has detachable connection parts 4,4 . . . on the side faces, which connect the closure in a line to otheradjacent closures when the closure and the other closures are connectedas a band of connected closures.

FIG. 2 shows cross-sections along line II-II in FIG. 1 illustrating thelayered structure of the closure 1 of this embodiment. The layeredstructures shown here are illustrative, and the layered structure of thepresent invention is not limited thereby.

The closure 1 shown in FIG. 2( a) has a three-layer structure comprisingpaper (11), synthetic resin (12) and paper (13) in that order from thetop. The synthetic resin here is preferably polyethylene terephthalateor polyethylene. The closure 1 shown in FIG. 2( b) has a three-layerstructure comprising synthetic resin (14), paper (15) and syntheticresin (16) from top to bottom. The closure 1 shown in FIG. 2( c) has afive-layer structure comprising polyethylene terephthalate (17),polyethylene (18), paper (19), polyethylene (20) and polyethyleneterephthalate (21) from top to bottom. The closure 1 shown in FIG. 2( d)has a four-layer structure comprising polyethylene terephthalate (22),polyethylene (23), paper (24) and polyethylene terephthalate (25) fromtop to bottom. The closure 1 shown in FIG. 2( e) has a two-layerstructure comprising polyethylene terephthalate (26) and paper (27) fromtop to bottom. The closure 1 shown in FIG. 2( f) has a three-layerstructure comprising polyethylene terephthalate (28), polyethylene (29)and paper (30) from top to bottom. FIG. 2( g) is a cross-section of aclosure with a single-layered structure of paper (30).

In this case, the paper material and synthetic resin material can belayered together by melting and solidifying the synthetic resin materialon the surface of the paper material, or by first preparing the papermaterial and synthetic resin material separately and then sticking themtogether with an adhesive.

FIG. 3 is a plane view showing one example of a band of connectedclosures of an embodiment of the present invention.

In the band 36 of connected closures shown in FIG. 3, closures formed ofa composite layer having one layer of thick paper are attached together.

Closure holes for closing a bag or other object to be closed areprovided roughly in the center of closures, 31, 31 . . . of thisembodiment in the plane view. An opening smaller than the closure holeand communicating with the closure hole is formed at one end of theclosure. Each closure also has detachable connection parts 34, 34 . . .on the side faces for connecting the closure to other adjacent closuresin a line when they are connected in a band of connected closures.

A band 36 of connected closures of this embodiment is formed with theaforementioned connection parts 34, 34 formed on the side faces ofclosures 31 connected to each other in a line. Notches 35, 35 . . . areformed extending towards the inner layer on the surfaces of theconnection parts of each closure.

An example of the band of connected closures of the present invention isgiven below. However, the present invention is not limited by thisexample.

Example 1

For the comparative example, nine pieces of grey-colored paperboard(MARICOAT made by Hokuetsu Paper Mills, Ltd.) were prepared as closuresamples (single-layer samples).

Next, closure samples (composite layer) were prepared with thefive-layer structure shown in FIG. 2( c) and they had a laminatedstructure of PET/PE/grey-colored paperboard (paper)/PE/PET. The paperand PE were bonded by melting the polyethylene. The PE and PET (biaxialorientation) were laminated using an ether adhesive.

The polyethylene terephthalate layer was 12 μm thick and thepolyethylene layer was 60 μm thick.

The aforementioned closure samples were each cut into strips 2 mm wideby 100 mm long, which were modified under the following conditions.

(1) Samples left to dry for 12 hours or more in a thermostatic oven at50° C. (humidity 20%): storage under dry conditions

(2) Samples left for 12 hours or more at room temperature (humidity 55to 65%): storage under normal humidity conditions

(3) Samples immersed in water and left for 12 hours in a containermaintained at high humidity (humidity 85%) or more: storage under moistconditions

Sets of three samples for the respective types of samples (single-layersamples and composite layer samples) were each kept under each of theabove three types of conditions, and removed. One sample from each setwas selected, and bending stress was applied by folding once the sampleat a 90° angle to one surface of the sample (hereunder, “single fold”).Another sample was then selected, and bending stress was applied byfirst folding the sample at a 90° angle to one surface and then foldingit at a 90° angle to the other surface for a total of two folds(hereunder, “double fold”). Samples applied with no stress are referredto as “no fold”.

Both ends of each sample were held with chucks so that the longitudinaldirection of the strip-shaped sample is aligned up and down, and tensiletests were performed by moving the movable chuck upwards. The evaluationresults are shown in Table 1 below.

[Measurement Conditions]

Measurement equipment: Tensile tester (Orientec Corp. TENSILONRTC-1210A)

Sample width: 2 mm

Chuck movement speed: 300 mm/min

TABLE 1 Storage conditions Normal Dry humidity Moist No foldSingle-layer samples 15.4 15.4 13.0 Composite layer 30.5 27.1 23.9samples Single Single-layer samples 12.0 12.8 10.3 fold Composite layer25.6 25.9 22.4 samples Double Single-layer samples 6.1 8.6 10.4 foldComposite layer 23.4 24.2 21.2 samples (Unit: N)

Table 2 below shows the evaluation results of Table 1 as percentagesgiven the results for the “no fold” sample under each type of storageconditions as 100.

TABLE 2 Normal Dry humidity Moist No fold Single-layer samples 100 100100 Composite layer 100 100 100 samples Single Single-layer samples 7883 79 fold Composite layer 84 96 94 samples Double Single-layer samples40 56 80 fold Composite layer 77 89 89 samples (Unit: %)

Ordinarily, paper has the property of becoming hard and fragile whenleft under dry conditions. Under moist conditions, it becomes soft. Thatis, under dry conditions it becomes strong with respect to tension butweak with respect to bending. Under moist conditions, on the other hand,it becomes weak with respect to tension but resists crease formationwhen folded, with little change in breakability.

It can be seen from the evaluation results of Table 1 and Table 2 abovethat the samples left under the dry, normal humidity or moist conditionsall undergo a decrease in tensile strength when subjected to bendingstress. It is also shown that the decrease is greater with a double foldthan with a single fold.

Looking at the “moist, double fold” samples for example, there wasroughly 20% deterioration in the case of the paper single-layer sample,but less deterioration (about 11%) in the case of the composite layersample. Looking at the “dry, double fold” samples, there was about 60%deterioration in the case of the single-layer sample, but only about 23%in the case of the composite layer samples, indicating good effectsunder dry conditions.

From this it can be seen that a composite layer closure sample is moreresistant to bending stress than a paper single-layer sample due to thelayering of a highly flexible synthetic resin. Because the syntheticresin is also resistant to the influences of moisture, moreover, acomposite layer closure sample is also much stronger than a single-layerclosure sample.

Example 2

The same grey-colored paperboard (MARICOAT made by Hokuetsu Paper Mills,Ltd.) used in Example 1 was prepared.

60 μm-thick polyethylene resin was then prepared.

A composite layer consisting of 12 μm polyethylene terephthalate resinbonded to 60 μm polyethylene resin was also prepared.

Using these three kinds of samples, the pulled distance and tensilestrength of the test samples were measured using the tensile tester ofExample 1.

FIG. 4 is a graph showing the relationship between pulled distance andtensile strength of a single-layer sample (paper).

FIG. 5 is a graph showing the relationship between pulled distance andtensile strength of polyethylene resin.

FIG. 6 is a graph showing the relationship between pulled distance andtensile strength of a composite layer.

FIG. 7 is a graph showing the relationship between pulled distance andtensile strength of a composite layer of paper and polyethylenesynthetic resin.

FIG. 8 is a graph showing the relationship between pulled distance andtensile strength of a composite layer of paper and synthetic resin.

As shown in FIG. 4, the single-layer sample exhibited maximum strengthwhen pulled about 1 mm. It is thought that this was the point at whichthe sample tore.

As shown in FIGS. 5 and 6, a synthetic resin layer does not tear atabout 1 mm in the same way as paper. Up to about 3 mm strength increasesproportionally, after which the resin exhibits a stable strength valuewithout tearing and then tears. The inclination angle of the curve andthe displacement before tearing differ depending on the type ofsynthetic resin.

FIG. 7 shows results for 60 μm polyethylene resin laminated on bothsides of paper, while FIG. 8 shows results for a composite layer of 60μm polyethylene resin and 12 μm polyethylene terephthalate resinlaminated on both sides of paper. As shown in FIG. 7, the resultinggraph is roughly what would result from combining the graphs for thesingle-layer samples of FIGS. 4 and 5. The graph obtained in FIG. 8 isroughly what would result from combining the graphs of FIGS. 4 and 6.

Thus, it is possible to adjust the strength by changing the type ofsynthetic resin. Moreover, while the connection parts of thesingle-layer samples break when pulled about 1 mm, laminating asynthetic resin allows for stable transportation because breakage doesnot occur even when the connection parts are pulled with strong pullforce.

The breaking strength of the connection parts can also be adjusted byadjusting the combination and thickness of the synthetic resin layers.

Example 3

Next, the amount of paper dust occurring when the paper is broken or cutwas tested by visual observation.

350 μm-thick paper (basis weight 280 g/m²) was prepared.

A composite layer was also prepared consisting of 60 μm-thickpolyethylene resin (PE) attached to both sides of the aforementionedpaper.

Each sample was cut into 30 mm width and 100 mm long strips, and afolding line was drawn across the width of each strip. Black sheets wereprepared, and each strip was subjected several times to bending stressalong the folding line atop the black sheet. Samples were torn along thefold line after five folds and after ten folds, and the amount of paperdust scattered on the black sheet was examined visually.

The results of observation are shown in Table 3. In the table, ◯indicates no fallen fibers (paper dust), Δ indicates that fibers (paperdust) of less than 1 mm fell, and x indicates that fibers (paper dust)of 1 mm or more fell.

TABLE 3 PE laminate on Times folded Paper only both sides 1 ◯ ◯ 5 Δ ◯ 10X Δ

When bending stress is applied multiple times to the same site, thefibers at the folding site become loose. When this area is torn, paperdust is likely to occur.

As shown in Table 3 above, when the synthetic resin PE is laminated onboth sides of paper, the fibers on the surface of the paper adhere tothe polyethylene resin and are held by it even under repeated bendingstress, resulting in very little paper dust.

Thus, it is possible by laminating synthetic resin on a layer formedfrom paper to prevent scattering of paper dust and suppress the problemof foreign matter contamination of the object to be closed.

Example 4

Two sheets (basis weight 600 g/m²) of grey-colored paperboard (MARICOATmade by Hokuetsu Paper Mills, Ltd.) were prepared for each sample.

Closure samples were prepared with the layered structures shown in FIGS.9( a) to (e) using this grey-colored paperboard. The closure samplesused in this example were bands of connected closures comprisingmultiple closures connected by their connection parts.

Sample 1: grey-colored paperboard (41)/80 μm PE (42)/grey-coloredpaperboard (41)

In the connection parts, the surface layers formed by paper on bothsides are cut, leaving the closures attached by the synthetic resinlayer (FIG. 9( a)).

Sample 2: grey-colored paperboard (41)/40 μm PE (42)/12 μm PET (43)/40μm PE (42)/grey-colored paperboard (41)

In the connection parts, the surface layers formed by paper on bothsides are cut, leaving the closures connected by the synthetic resinlayers (FIG. 9( b)).

Sample 3: grey-colored paperboard (41)/40 μm PE (42)/12 μm PET (43)/40μm PE (42)/grey-colored paperboard (41)

Notches are formed in the connection parts through about 2/3 ofthickness of the surface of both surface layers formed from paper,leaving the closures connected by the synthetic resin layers and bythinned layer of paper (FIG. 9( c)).

Sample 4: grey-colored paperboard (41)/40 μm PE (42)/12 μm PET (43)/40μm PE (42)/grey-colored paperboard (41)

In the connection parts, one of the surface layers formed of paper iscut, leaving the closures connected by a layer of synthetic resin and asingle layer formed of paper (FIG. 9( d)).

Sample 5: grey-colored paperboard (41)/40 μm PE (42)/12 μm PET (43)/40μm PE (42)/grey-colored paperboard (41)

No notches are formed in the connection parts (FIG. 9( e)).

A connection strength test was performed using the bands of connectedclosures described above. Connection strength was measured in twodirections, i.e., in the direction of feed and in the direction ofacross-the-width.

Connection strength in the direction of feed was measured as shown inFIG. 10 by securing closures 51 and 51 connected by connection parts 52with chucks 55 and 56 disposed above and below the closures, exertingperpendicular pull, and measuring the strength at the time that theconnection parts of the adjacent closures were detached.

Connection strength in the across-the-width direction was measured asshown in FIG. 11 by securing closures 51 and 51 connected by connectionparts 52 and 52 with chucks 55 and 56 disposed above and below theclosures, exerting perpendicular pull, and measuring the strength at thetime when the connection parts of the adjacent closures were detached.

The results are shown in Table 4.

TABLE 4 Tensile strength in Sample Tensile strength in across-the-widthNo. direction of feed direction 1 1.3 1.2 2 4.8 5.1 3 6.5 7.3 4 9.7 10.45 15.3 16.2 (Unit: N)

As shown in Table 4 above, Sample No. 4 having notches formed on thesurface of one side of the connection parts on the band of connectedclosures had less detachment strength in both the direction of feed andthe across-the-width direction than Sample No. 5, which had no formednotches.

It can also be seen that Sample No. 3 having notches formed about 2/3 ofthe way towards the inner layer on both surfaces had less detachmentstrength than Sample No. 4. Samples No. 1 and No. 2 whose paper layersare severed in the connection parts had even less detachment strength,and Sample No. 1 in particular had particularly low detachment strengthin the across-the-width direction.

When an actual package product is closed with a closure, the idea isthat a band of connected closures is reeled out along guard rail 58 inthe direction of the arrow as shown in FIG. 12, and open ends 55 ofpackage products 54 which are being transported in the direction of thearrow by conveyor belt 52 or the like are inserted into the openingscommunicating with the closure holes at the center of closures 51 ashammer 57 is moved from the side of the closure in the direction of thearrow to hit the closure and detach it from the band.

In such a case, it is desirable that not only the tensile strength inthe direction of feed but also the tensile strength in theacross-the-width direction be somewhat low.

Example 5

One example of closures according to the present invention wasmanufactured and subjected to impact-resistance testing (drop test).

The closures prepared and used in this example were single-layer papersamples 22 mm long and 21 mm wide, with a basis weight of 280 g/m²(Sample 6), 440 g/m² (Sample 7), 560 g/m² (Sample 8), 840 g/m² (Sample9) and 1100 g/m² (Sample 10), and a commercial plastic closure(polystyrene, 800 μm thick, Sample 11) was also prepared.

The impact resistance test was performed as follows.

First, a one-loaf bread bag was inflated with air, and the opening wasclosed with the closure.

Next, the closed bread bag was placed on a smooth floor. A square weightwas then dropped towards the top of the bag from the specific heightsshown in Table 5 below, in such a way that the bottom face of the weightremained level.

The degree of damage to the closure from the shock of the falling weightwas observed visually. The results are shown in Table 5.

In Table 5, ◯ means no damage to the closure, and x means the closuretore or was detached from the opening of the bag.

TABLE 5 Drop height (mm) Sample 30 50 100 300 600 900 6 X — — — — — 7 ◯◯ X — — — 8 ◯ ◯ ◯ ◯ X — 9 ◯ ◯ ◯ ◯ ◯ X 10 ◯ ◯ ◯ ◯ ◯ ◯ 11 ◯ ◯ ◯ ◯ X —

As shown above, in the case of Sample 6 with a basis weight of 280 g/m²,the closure was too soft and the binding strength insufficient.

Example 6

A bending strength test was performed using the closures prepared inExample 5.

The bending strength test was performed by the method shown in FIG. 13using a tensile tester (TENSILON RTC-1210A, made by Orientec Co.).

Using a closure shown in FIG. 13( a), two strings 63 and 64 were tied toeither side of opening 62 of closure 61 as shown in FIG. 13( b), andsecured to chucks 65 and 66 located above and below the closure.

In this state chucks 65 and 66 were moved up and down, respectively asshown in FIG. 13( c), and the strength was measured when the openingreached 10 mm. The results are shown in Table 6.

TABLE 6 Sample No. Strength 6 0.1 7 0.7 8 0.75 9 2.0 10 2.4 11 1.25(Unit: N)

It appears from looking at the results of Table 6 that Sample 6 with abasis weight of 280 g/m² could detach because it would not be able towithstand the rigidity of the bag. On the other hand, Sample 10 with abasis weight over 1000 g/m² was rigid itself and thus the closure wasdifficult to clip around the opening of a bag by fingers.

It was confirmed from the results of Table 5 and Table 6 that paper witha basis weight of 440 g/m² to 840 g/m² can be preferably used.

Example 7

Closures were prepared using food packaging paper with relatively longfibers (100% virgin pulp, no recycled paper) and a basis weight of 350g/m², with connection parts on the sides, to prepare a band of connectedclosures in which the adjacent connection parts were connected to eachother in a line (Sample 12).

A band of connected closures was also prepared using the grey-coloredpaperboard (MARICOAT made by Hokuetsu Paper Mills, Ltd.) with relativelyshort fibers and a basis weight of 600 g/m². Each closure was providedwith connection parts on the side faces that were connected in a line toadjacent connection parts to prepare a band of connected closures(Sample 13).

A connection strength test was performed using these bands of connectedclosures.

As shown in FIG. 11, closures 51 and 51 connected by connection parts 52and 52 were secured with chucks 55 and 56 arranged above and below theclosures, perpendicular pull was exerted, and the strength was measuredat the time that the connection parts of the closures were detached.

The results are shown in Table 7.

TABLE 7 Sample Measurement 600 g/m² No. value conversion 12 8.0 13.7 139.2 9.2 (Unit: N)

As shown in Table 7 above, Sample 13 with relatively short fibers hadless connection strength than Sample 12 with relatively long fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plane view showing one example of a closure of an embodimentof the present invention.

FIG. 2 is a cross-section along an arrow II-II showing a closure 1 ofthe embodiment shown in FIG. 1.

FIG. 3 is a plane view showing part of a band of connected closures ofanother embodiment of the present invention.

FIG. 4 is a graph showing the relationship between pulled distance andtensile strength for a single-layer sample (paper).

FIG. 5 is a graph showing the relationship between pulled distance andtensile strength for polyethylene.

FIG. 6 is a graph showing the relationship between pulled distance andtensile strength for a composite layer.

FIG. 7 is a graph showing the relationship between pulled distance andtensile strength for a composite layer of paper and polyethylenesynthetic resin.

FIG. 8 is a graph showing the relationship between pulled distance andtensile strength for a composite layer of paper and synthetic resin.

FIG. 9 shows cross-sections of the closures of Example 4, which consistof layers of paper and synthetic resin.

FIG. 10 is an outline explaining a connection strength test in thedirection of feed performed using the band of connected closures ofExample 4.

FIG. 11 is an outline explaining a tensile strength test in theacross-the-width direction using the bands of connected closuresaccording to Examples 4 and 7.

FIG. 12 is an outline showing one example of a method for closing anobject to be closed using a closure according to an embodiment of thepresent invention.

FIG. 13 is an outline explaining the bending strength test performed inExample 6.

EXPLANATION OF REFERENCE NUMERALS

-   -   1, 31, 51, 61 Closure    -   2 Closure hole    -   3, 62 Opening    -   4, 34, 52 Connection part    -   11, 13, 15, 19, 24, 27, 30, 41 Paper layer    -   12, 14, 16, 17, 18, 20, 21, 22, 23, 25, 26, 28,    -   29, 42, 43 Synthetic resin layer    -   35 Notch    -   36 Band of connected closures

1. A closure having a closing function and reclosability, which isformed of a composite layer having at least a layer formed of paper, andwhich has a closure hole, provided substantially in a center part, forclosing an object to be closed, and which is further provided with, atone end, an opening that is smaller than the closure hole, the openingcommunicating with the closure hole, wherein at least one of layer orlayers other than the paper layer is formed from synthetic resin and/orbiodegradable resin, the closure comprises, on side faces, detachableconnection parts that are connected to other closures adjacent theretothat are in a line with the closure, when the closure and the otherclosures are formed as a band of connected closures and one or morenotches are formed at the detachable connection parts at least in thelayer formed of paper.
 2. (canceled)
 3. (canceled)
 4. The closureaccording to claim 1, wherein the layer formed from the synthetic resinand/or biodegradable resin includes an oriented film.
 5. The closureaccording to claim 1, wherein the closure is formed of a composite layercomprising layers made of paper that are laminated on both surfaces ofthe layer of synthetic resin and/or biodegradable resin.
 6. The closureaccording to claim 1, wherein the closure is formed of a composite layercomprising the layers of synthetic resin and/or biodegradable resinlaminated on both surfaces of the layer of paper.
 7. The closureaccording to claim 1, wherein the layer of synthetic resin is formedfrom any one of olefin resin, polyethylene terephthalate (PET),polystyrene (PS), acrylonitrile (AN) and polyvinyl alcohol (PVA).
 8. Theclosure according to claim 1, wherein one or more notches are formed inthe connection parts of the closure from one or both surfaces thereoftowards an inner layer.
 9. The closure according to claim 1, whereinonly the layer made of paper at the connection parts of the closure issevered.
 10. The closure according to claim 1, wherein the weight perunit area of the paper is 400 to 1000 g/m².
 11. The closure according toclaim 1, wherein the average length of fibers making up the paper is 1.0mm to 4.0 mm.
 12. The closure according to claim 1, wherein ink or acoating material is printed or coated on the surface of the closure. 13.A band of connected closures formed by connecting the closures accordingto claim 1 in a line by means of the adjacent connection parts of theclosures.
 14. A package product wherein the object to be closed isclosed using the closure according to claim 1.